Application of new functions as well as new accessories in electronics field is becoming increasingly popular. Due to a development trend to higher processing power and broader application, heat generated by a device is also largely increased; meanwhile, integration level for parts keeps increasing, and the electronic device tends to get miniaturized. On one hand, the electronic device is becoming smaller; on the other hand, the power consumption of the electronic device is increasing. A direct result of this is an increasing heat flux density within the device, with a dramatic increase on cost as well as much more difficulty in heat dissipation, which forms a bottleneck during designing. Thus, under plural restrictive conditions in actual products, there exists an urgent need to solve the problem how to effectively dissipate heat generated by parts which are arranged on a circuit board in a high density.